cmake: add_custom_command fix empty and quoted parameters

mesonbuild/cmake/data/run_ctgt.py

@@ -28,6 +28,7 @@ for i in args.commands:
         commands += [[]]
         continue
 
+    i = i.replace('"', '')  # Remove lefover quotes
     commands[-1] += [i]
 
 # Execute

mesonbuild/cmake/interpreter.py

@@ -461,6 +461,8 @@ class ConverterCustomTarget:
             cmd = []
 
             for j in i:
+                if not j:
+                    continue
                 target_key = _target_key(j)
                 if target_key in output_target_map:
                     cmd += [output_target_map[target_key]]